The present invention relates to apparatus for dispensing liquid soap, normally in discrete small quantities or charges. Such dispensing apparatus is used particularly for hygienic purposes, in public or institutional washrooms or the like or wherever there are a relatively large number of different users.
The invention is an improvement over the device disclosed in U.S. Pat. No. 5,082,150 issued Jan. 21, 1992, entitled "Liquid Dispensing System Including a Discharge Assembly Providing A Positive Air Flow Condition", and U.S. Pat. No. 5,174,476 issued Dec. 29, 1992, entitled "Liquid Soap Dispensing System", the entire disclosures of which including all drawing figures are incorporated by reference.
One prior type of soap dispenser utilizes a container or cartridge of liquid soap which is removably mounted on a dispensing apparatus so that it can be replaced by another cartridge when it is empty. Such a dispenser is disclosed in U.S. Pat. No. 1,326,880. However, the soap container of that dispenser is of the refillable type. This means that the spent containers must be collected, sterilized and refilled and sealed for reuse, which is a time consuming and expensive operation. Because the container is refillable, it has a refill opening which, although normally closed, is accessible to users and could permit contamination of the contents or refilling with soap from an unauthorized source. Furthermore, the container is readily removable from the dispenser by any user, so that the entire container could easily be replaced by a "bootleg" container.
To avoid this problem, it is known to provide dispensers with closed, lockable cabinets in which the refill cartridge or container is enclosed, so as to prevent access by unauthorized persons. But this type of housing is relatively expensive. Furthermore, such prior dispensers have relatively complex construction, frequently using a large number of parts, the assembly of which entails substantial labor.
Efforts have been made to simplify the design of soap dispensers with replaceable cartridges while retaining the ability to restrict access to the dispenser, for instance refer to U.S. Pat. Nos. 4,673,109 and 4,886,192. While solving the problem of design simplification for easier maintenance as illustrated in the construction of the '109 and '192 patents, there has arisen the problem of dispensing doses of soap upon rapid and repeated (5-15) compressions of the nipple.
Repeated attempts to solve this problem of increasing suction are evidenced by U.S. Pat. Nos. 4,646,945, 4,673,109, 4,930,667, 5,082,450 and 5,174,476 by Steiner Company, Inc., but have not proven completely successful. No matter how many different attempts have been made, the result has always been subject to commercial problems.